350 horsepower?

[MustangSix]

In for a penny, in for a pound.

Once you decide to use EFI, why saddle yourself with a TBI? Take Mike's suggestion to use a Mustang TB and drill the manifold for port injectors. Two feet of fuel rail, a regulator, and some hold downs. Maybe two hours on a drill press and some -an fittings.

To get to 350 hp you'll need six ~42lb injectors (~440cc) assuming a forced induction BSFC of around .62 lbs/hp/hr.

I've driven and owned both blown and turboed cars. The last car was a factory turboed Mazdaspeed Miata; the current one is a turbo CX-7. Both fun in their own way. I also had a new 1985 Mustang SVO. I like turbos.

But the supercharged T-bird is a kick to drive as are the FWD GM 3800 powered cars. Zero lag in those. And I once had an MGA with a Shorrock blower on it. That was fun, too. I wish there was a supercharger package that I could put on my wife's Camry.

Each has distinctive characteristics and requirements for mounting and packaging. Either can be made to perform very well (or very poorly). To hold up either as "best" is a specious argument because they each have merit.

 

[rommaster2]

I don't quite understand the reference in Mikes earlier post that says that superchargers are one of the best ways to increase power and still keep mileage relatively untouched.

Isn't that impossible because you are always on boost therefore you must use more fuel or you will lean out and burn your pistons?

That was actually the reason a turbo seemed like a better idea to me, sure it has a little lag, but with proper gearing that is negligible and i could cruise at lower rpm to keep the boost down and get the same gas mileage as a non boosted car.

I'm not trying to argue, i think either kit would be cool and options for varias degrees of builds should be there because a turbo while it is cool and more efficient is also a little more work involved in putting it in and tuning it properly so for the every day guy they would not be too interested in that. I'm just trying to understand something that seems to defy the laws of nature .

 

[Bort62]

I don't quite understand the reference in Mikes earlier post that says that superchargers are one of the best ways to increase power and still keep mileage relatively untouched.

Isn't that impossible because you are always on boost therefore you must use more fuel or you will lean out and burn your pistons?

That was actually the reason a turbo seemed like a better idea to me, sure it has a little lag, but with proper gearing that is negligible and i could cruise at lower rpm to keep the boost down and get the same gas mileage as a non boosted car.

I'm not trying to argue, i think either kit would be cool and options for varias degrees of builds should be there because a turbo while it is cool and more efficient is also a little more work involved in putting it in and tuning it properly so for the every day guy they would not be too interested in that. I'm just trying to understand something that seems to defy the laws of nature .

There is an important distinction here that many don't seem to be highlighting - and that is the difference between positive displacement superchargers (M90, Detroit 4-71, 8-71, Magnacharger, etc) and centrifugal superchargers (Paxton, Vortec, ATI, etc).

Positive displacement or screw type superchargers tend to be more in the "boost all the time" category.

Centrifugal superchargers are basically the compressor section of a turbo being driven by a belt instead of a turbine.

As such, Centrifugal superchargers perform similarly to turbos, building boost as RPM and load increases. At part throttle, there is little to no effect.

Screw type superchargers produce boost essentailly immediately as a load is placed on the engine. This is what makes them so much "fun" on the street because that insta-boost provides neck snapping acceleration and tire burning off idle power.

But they tend to peter off pretty bad at high RPM and then you got nothing.

While all means of forced induction typically reduce fuel economy, positive displacement certainly is the worst offender.

However, properly tuned, there should be little to no difference.

 

[Does10s]

What is this, everyone argue with AzCoupe month?......

We're just havin' some fun!

Will

 

[350kmileford]

What sort of TBI would I use to support high power levels? I know I could go with individual throttle bodies and injectors, but that gets VERY expensive. The Tempo TBI can't flow nearly enough fuel. Could I somehow utilize a TBI from a V8 application? What to do . . .

We'll be making adaptor plates for 5.0L throttle bodys, which will give you a wide selection of new or used.

Well, what would I do about the injector? I'd have to rig something?

Someone answer my question about cfm rating?

 

[Bort62]

CFM ratings for TB's are typically different than they are for carbs.

A CFM # is useless without a corresponding pressure drop.

 

[HUMINA]

Positive displacement or screw type superchargers tend to be more in the "boost all the time" category.

One of the benefits of the Eaton superchargers used by OEMs is that they have some sort of bypass system to eliminate boost when it isn't needed. The supercharger is always spinning but their is no pressure being built when it isn't needed, so the load isn't significant.

My friend and I both had Pontiac Grand Prix. Mine was a simple GT and his was the GTP (Eaton supercharger). His was rated for 45 more HP and 50 more ft/lb. EPA ratings were worse by 1/3 MPG. Essentially, driving style had a far bigger impact on the fuel economy.

My opinion is that a roots type supercharger is great for off the line, kick in the pants acceleration. Even well done turbos have some small lag time, they are great for building power and have the capacity to build huge amounts of boost, but it isn't there off the line.

Like a lot of discussions, it comes down to what your driving style is and what kind of feel you want in the car.

 

[wallaka]

Positive displacement or screw type superchargers tend to be more in the "boost all the time" category.

One of the benefits of the Eaton superchargers used by OEMs is that they have some sort of bypass system to eliminate boost when it isn't needed. The supercharger is always spinning but their is no pressure being built when it isn't needed, so the load isn't significant.

Only the most modern, Gen V superchargers do this. The more common Thunderbird SC and 3800 Gen IV do not have any kind of bypass on them.

 

[MustangSix]

What sort of TBI would I use to support high power levels? I know I could go with individual throttle bodies and injectors, but that gets VERY expensive. The Tempo TBI can't flow nearly enough fuel. Could I somehow utilize a TBI from a V8 application? What to do . . .

We'll be making adaptor plates for 5.0L throttle bodys, which will give you a wide selection of new or used.

Well, what would I do about the injector? I'd have to rig something?

Someone answer my question about cfm rating?

Mikes manifold is designed so that you can drill it for port injectors. There is a special bit that you could use to do it all in one pass or you could do it with multiple tools. Most Bosch/Rochester style injectors have a common dimension. To supply the injectors you need to connect them to the fuel source. Usually that's an aluminum extrusion that, like the manifold, is drilled so that the supply end of the injectors fit in. On one end of the tube you feed fuel, on the other you bleed off excess pressure thru a regulator. You need a way to hold the fuel rail down.

CFM on a fuelie car with a dry flow manifold is not as critical as it is on a carb. It's just an air valve, so you aren't faced with the compromises on things like venturi sizing and fuel flow like you are on a carb. Carbs are sized the way they are because you have to maintain velocity in the carb in order to control fuel flow. Simplistically and within reason, velocity thru the TB is irrelevant except for controlling the rate of opening so that throttle engagement is smooth.

The 65mm TB from a stock Mustang would probably flow 700cfm if you measured ti the same as a carb. It'll work fine on a port injected 200. The TB I'm using on the Crossflow is 70mm.

Take a look at the www.sdsefi.com tech page for ideas.

 

[350kmileford]

Long story short, it looks like I'll be going back to school soon (wasn't my initial pan) so my budget is basically slaughtered. I will be getting an aluminum head, but it will probably be at least a year before I can afford one. I think I am going to go with an Eaton setup on a log head now.

I will probably run an Eaton unit on the log head now; using a 350 cfm carb.

Another random question, I saw in another topic, a guy was running an M90, however it was upside down. I understand this wouldn't effect flow in any way, but could this hurt lubrication?

Fair warning, the Eaton M90's DON'T have sealed rear case bearings and Fuel can get at them in a suck through setup. I have lots of experiance with M90's owning a supercoupe.

What would be the solution to this?

 

[Patrick66]

Fair warning, the Eaton M90's DON'T have sealed rear case bearings and Fuel can get at them in a suck through setup. I have lots of experiance with M90's owning a supercoupe.

What would be the solution to this?

use a blow through setup.

 

[350kmileford]

Yea this morning I read through a surprising number of M90 topics. Seems like I will spend some extra time and money, and go blow through and probably intercooled. Any reason not to intercool?

 

[grocery getter]

Yea this morning I read through a surprising number of M90 topics. Seems like I will spend some extra time and money, and go blow through and probably intercooled. Any reason not to intercool?

I sent you a pm on the m90. Go intercooler, it's cheap HP.